地质高背景区晚疫病马铃薯根际土壤细菌群落对重金属胁迫的响应

Response of Rhizosphere Bacterial Community of Potato Infected by Late Blight to Heavy Metal Stress in High Geological Background Area

探究地质高背景区重金属胁迫下晚疫病马铃薯根际土壤细菌群落变化及其影响因素,对马铃薯安全生产具有重要意义。采集马铃薯(‘青薯9号’‘威芋5号’和‘威芋3号’)健康植株和晚疫病发病植株根际土壤,检测土壤p H、有机质和重金属含量,用Illumina MiSeq高通量测序技术分析细菌群落;采集马铃薯块茎,测定重金属含量。试验区土壤Cd、Cr和Zn含量均值分别为2.14、170和220 mg/kg,Cd含量超过国家土壤质量标准风险管制值,Cr和Zn含量超筛选值。马铃薯块茎仅1个样品Cd含量为0.103 mg/kg,超过国家食品安全限值标准。发病马铃薯根际土壤优势细菌门及其相对丰度主要为变形菌门(Proteobacteria)33.16%~39.09%、放线菌门(Actinobacteria)13.45%~17.11%;优势菌属主要为鞘脂单胞菌属(Sphingomonas)8.78%~12.30%、芽单胞菌属(Gemmatimonas)6.22%~7.61%,发病植株优势菌相对丰度与健康植株存在差异。不同品种间细菌多样性与丰度不同,马铃薯感染晚疫病后根际土壤细菌群落多样性升高,细菌菌群丰度下降。主成分分析显示发病植株与健康植株细菌群落差异性贡献率为29.59%。冗余分析结果表明,土壤重金属和pH显著影响土壤细菌群落组成和结构,对优势菌群的影响尤为明显,健康与发病植株间细菌群落的差异受土壤Pb、Cr胁迫的影响更大。因此,地质高背景区重金属胁迫下马铃薯可实现安全生产,染病马铃薯植株根际土壤细菌群落多样性降低,丰富度上升,土壤Pb、Cr通过改变根际土壤细菌群落有益菌类而影响晚疫病的发生和发展。

Exploring the changes in the bacterial community and its influencing factors in the rhizosphere soil of late blight-affected potatoes under heavy metal stress in a geologically high background area is crucial to guarantee the safety of potato production.Rhizosphere soil samples were collected from both healthy and late blight-diseased potato plants('Qingshu 9','Weiyu 5'and'Weiyu 3').Subsequently,the soil pH,organic matter content and heavy metal concentrations were analyzed.The bacterial community was analyzed using Illumina MiSeq high-throughput sequencing,while the heavy metal content in the potato tubers was determined simultaneously.In the soil of the tested area,the mean concentrations of Cd,Cr and Zn were 2.14,170 and 220 mg/kg,respectively.Cd levels exceeded the risk control threshold of the national soil quality standard,while Cr and Zn levels exceeded the screening values.Among the potato tuber samples,only one exhibited a Cd concentration of 0.103 mg/kg,exceeding the national food safety limit standard.The predominant bacterial phyla and their relative abundances in the rhizosphere soil of diseased potatoes were Proteobacteria(33.16%-39.09%)and Actinobacteria(13.45%-17.11%);the predominant bacteria were primarily Sphingomonas(8.78%-12.30%)and Gemmatimonas(6.22%-7.61%).The relative abundance of dominant bacteria differed in diseased plants compared to healthy plants,with variations observed among different plant varieties in terms of bacterial diversity and abundance.After potato late blight infection,there was an increase in the diversity of the bacterial community in the rhizosphere soil,while the abundance of the bacterial community decreased.Principal component analysis revealed that the contribution rate of bacterial community differences between diseased plants and healthy plants was 29.59%.The results of redundancy analysis indicated that soil heavy metals and pH had a significant impact on the composition and structure of the soil bacterial community,particularly on the dominant bacteria.The differences in the bacterial community between healthy and diseased plants were more influenced by soil stress from Pb and Cr.Therefore,potatoes could achieve safe production even under heavy metal stress in high geological background areas.In the rhizosphere soil of infected potato plants,the diversity of the bacterial community decreased while the richness increased.The occurrence and development of late blight were affected by soil Pb and Cr through alterations in the beneficial bacteria within the rhizosphere soil bacterial community.